Admiral, you get to make your own rules for this - if that small amount of alcohol doesn't bother you, simply pay no attention to the people who tell you that it should. If you have always eaten your oatmeal with vanilla flavoring, it may have nothing to do with your sobriety.
There is a trace amount of alcohol in your oatmeal, true, but there are also trace amounts in many common foods, and trying to eliminate all of them can lead to some pretty bizarre behavior like eliminating all fresh fruit, bread, or soft drinks because of their alcohol content. I think that would be a silly thing for me to do, maybe for you to do too.
If, on the other hand, the idea of adding vanilla to your oatmeal squicks you out because of your aversion to its alcohol content, no matter how small, then by all means don't add it, or add something else. Totally your call here.